<!doctype html>
<head>
  <style>
    /* keep the spans from bleeding off the top of the page */
    body {
      margin: 1.5em;
    }

    .box {
      padding: 1em;
      border-radius: 1em;
      background-color: lightgray;
    }

    .box-small {
      font-size: 12px;
    }

    .box-large {
      font-size: 18px;
    }
  </style>
</head>

<body>
  <span class="box box-small">Small</span>
  <span class="box box-large">Large</span>
</body>
